Consequential Life Cycle Assessment Research Articles

Consequential life cycle assessment of kraft lignin recovery with chemical recycling

The recovery of kraft lignin from black liquor allows an increasing of the pulp production of a kraft mill (marginal tonnage) and at the same time provide a valuable material that can be used as energy or chemical feedstock. However, because lignin precipitation is an energy- and material-consuming process, the environmental consequences from a life cycle perspective are under discourse. The aim of this study is to investigate, through the application of consequential life cycle assessment, the potential environmental benefits of kraft lignin recovery and its subsequent use as an energy or chemical feedstock. A newly developed chemical recovery strategy was assessed. The results revealed how the use of lignin as energy feedstock is not environmentally advantageous compared to producing energy directly from the pulp mill's recovery boiler. However, the best results were observed when lignin was used as a chemical feedstock in four applications to replace bitumen, carbon black, phenol, and bisphenol-A.

Life Cycle Assessment Applied to End-of-Life Scenarios of Sargassum spp. for Application in Civil Construction

Environmental risks and vulnerabilities in coastal regions include the massive deposits of brown algae of the genus Sargassum in regions such as the Caribbean, Gulf of Mexico, and northern Brazil. Efforts have been made to turn this problem into an opportunity by seeking new uses for this biomass in the sectors of food, agriculture, health, biofuels, bioremediation, and civil construction. Thus, this study aimed to produce quantitative data for different end-of-life scenarios of the Sargassum algae, seeking for potential applications of this macroalgae in the civil construction sector. For this purpose, we conducted a life cycle assessment (LCA) study of the Sargassum algae, in its natural destination, and evaluated its potential impact. This evaluation was then compared to the possible impacts of alternatives to their end of life, such as landfill disposal, drying and grinding to use as fibers or particles, burning the biomass to generate energy and fly ash, using a consequential LCA and the indicators of the ReCiPe 2016 method. For each of the proposed scenarios, the functional unit of 1 kg of the three types of unprocessed Sargassum algae that are found in the Brazilian deposits (natans I, natans VIII, and fluitans) was considered separately, and also for a composition that is closer to that found in the Brazilian deposits (50% fluitans, 15% natans I, and 35% natans VIII). The results for both natural decomposition scenarios demonstrated a dominant contribution to the categories of impact for climate change, marine eutrophication, and land use, thus justifying the search for new initiatives for the use of the algae. The burning process showed a significant contribution to most of the indicators, with emphasis on the massive generation of particulate, inherent to the biomass burning process; however, it showed a reduction in the magnitude of climate change emissions from around 47% to less than 2%. Finally, the proposed scenario of processing Sargassum biomass to obtain particles presented prevalence of magnitude for potential impact in most of the proposed indicators, due to the processes with high electricity consumption, but keeping climate change emissions’ relative reduction from 47% to 6%. Thus, new studies may further investigate the potential of application of these materials in different products and components of civil construction.

Consequential Life Cycle Assessment of Grain and Oilseed Crops: Review and Recommendations

The field crop industry in Canada is a source of both significant economic benefits and environmental impacts. Environmental impacts include land and energy use, as well as greenhouse gas (GHG) and other emissions. Impacts also accrue upstream of the field in the product supply chain, from the production of such inputs as fertilizers and pesticides. There are currently two types of environmental life cycle assessment (LCA)—attributional LCA (ALCA) and consequential LCA (CLCA)—that may be used to study the life cycle impacts of products such as field crops. ALCA is a retrospective methodology that presents a snapshot of average, “status quo” conditions. CLCA is a prospective methodology that presents the potential implications of changes in a product system, including any associated market-mediated changes in supply or demand in other product systems. Thus, CLCAs can be used to assess large-scale changes in the field crop industry, including its relationship to other sectors and processes, such as the production of biofuel or of food for both human and animal consumption. The aim of this paper is to review and curate the knowledge derived through published CLCA studies that assessed the impacts of changes to field crop production systems on the life cycle resource use and emissions associated with the agricultural products, with a focus on their relevance to temperate climate conditions. The current study also highlights how previous studies, including ALCAs and farm management recommendations, can be used to inform the changes that should be studied using CLCA. The main challenges to conducting CLCAs include identifying the system boundaries, marginal products and processes that would be impacted by changes to field crop production. Marginal markets and product systems to include can be determined using economic equilibrium models, or information from local experts and industry reports. In order to conduct ISO-compliant CLCAs, it is necessary to include multiple relevant environmental impact categories, and to perform robust data quality and uncertainty analyses.

Life cycle assessment of power generation systems in Spain: Exploring a broader view from a consequential perspective

Developing new clean power generation systems is a research priority for the energy sector, and selection should be based on environmental performance over the entire lifetime. Consequential Life Cycle Assessment evaluates the consequences of this selection and provides environmental data to support decision-making. This research uses a consequential approach to assess the environmental impacts of two medium power generation systems. The selected environmental impact assessment methods are IPCC 2013 GWP 100y and ReCiPe 2016. Moreover, the work describes a methodology for finding the marginal mix technologies for electricity and cooling energy production depending on the time horizon. The positive environmental consequences associated with short-term marginal energy mixes (electricity and cooling) progressively disappear when the marginal energy mix varies throughout time. The environmental results strongly depend on the marginal mix of technologies and evidence the necessity to develop methodologies and standards to improve the robustness of environmental assessments. A new line of discussion is opened concerning the temporal variation of environmental impacts of an energy production system, which could also be considered in Attributional Life Cycle Assessments.

A biorefinery platform to valorize organic fraction of municipal solid waste to biofuels: An early environmental sustainability guidance based on life cycle assessment

The biorefining of biowastes, specifically the organic fraction of municipal solid waste (OFMSW), into biofuels and high-value products is an energy-demanding process, still immature, and largely dependent on the process configuration and efficiency of employed microorganisms. Such issues might undermine the environmental sustainability of the biorefinery by inducing adverse impacts on human health, ecosystem quality, climate change, and resources, which need to be explored before the process scale-up. Hence, this study was performed as early sustainability guidance to investigate the environmental impacts of different biorefinery platforms for biofuels production from OFMSW. More specifically, three pretreatment methods (i.e., acetone organosolv, acid, and hot water), two hydrolysis treatments (i.e., acidic and enzymatic), and two fermentation alternatives (i.e., ethanolic fermentation and acetone-butanol-ethanol (ABE) fermentation) were investigated. Based on European Commission's Joint Research Center instruction, the environmental impacts were studied using consequential life cycle assessment for the macro-level decision context. The results demonstrated that ABE fermentation scenarios were not environmentally favorable because the avoided impacts from final products were not significant enough to compensate for the induced environmental burdens from acetone pretreatment. On the contrary, the ethanolic fermentation scenarios with either acid or hot water pretreatment outperformed both ABE fermentation and ethanolic fermentation with acetone pretreatment. Based on the results, the scenario including simultaneous dilute acid pretreatment and hydrolysis of OFMSW followed by ethanolic fermentation manifested the best performance in all damage categories, as compared to those including acetone pretreatment or higher consumption of enzymes. Such improvements in this scenario led to the highest net saving of −842 potentially disappeared fraction (PDF)/m2/yr, −249.95 kg CO2 eq, and −3275.22 MJ primary per ton of OFMSW on ecosystem quality, climate change, and resources, respectively, and the lowest net burden of 1.54 × 10-5 disability-adjusted life years (DALY) per ton of OFMSW on human health. The results of sensitivity analysis on this scenario demonstrated that the substitution of excess heat for marginal heat with fossil origin can considerably decrease impacts on human health.

Use of life cycle assessment to evaluate circular economy business models in the case of Li-ion battery remanufacturing

PurposeThe purpose of this study is to advance and illustrate how life cycle assessment (LCA) can assess circular economy business models for lithium-ion batteries to verify potential environmental benefits compared to linear business models. Scenarios for battery repurpose are assessed to support future decision-makers regarding the choice of new versus second life batteries for stationary energy storage. A procedure to determine the substitution coefficient for repurpose and reuse of batteries is proposed.MethodsTwo different circular economy business models are assessed by applying primary data from two Norwegian companies for the development of a new life cycle inventory. With this new data, the authors compare second life battery (from first life in electric vehicle) scenarios and avoided production potential by performing a complete consequential LCA. Building on earlier work, a procedure to identify the substitution coefficient (i.e., potential for avoided production) for battery life cycle assessments is proposed. Interviews during factory visits were performed to identify a technical and a market factor affecting the substitution coefficient.Results and discussionThis study illustrates how life cycle assessment methodology can detect and thus enhance the potential environmental benefits and trade-offs of circular economy business models. Results show that the CBMs which use second life batteries correspond to 16% (for global warming potential) of manufacturing a new battery. This means that a second life battery must avoid > 16% production of a new battery to become the preferred alternative. Hence, circular economy business models with second life batteries can generate net environmental benefits while the remaining battery capacity and market price are identified factors that can alter the potential environmental benefits. The findings suggest that assumptions concerning the avoided production emissions are crucial for understanding the overall impacts of battery value chains.ConclusionsCircular economy business models which enable second life batteries show lower environmental impacts compared to a new battery when it can partly avoid production of a new battery. Based on the identified technical and market factor affecting this potential, a key message to industry and other organizations is that second life batteries should be chosen over new batteries. This depends on the remaining capacity being satisfactory for the new application, and the investment is not performed because of a low price compared to a new battery. Consequential LCA practitioners adopting a market approach while evaluating battery reuse and repurpose should model and account for the avoided production potential.

Do Carbon Footprint Estimates Depend on the LCA Modelling Approach Adopted? A Case Study of Bread Wheat Grown in a Crop-Rotation System

This study aims to assess the impact of global warming on winter wheat cultivation under different rotation systems with potato, maize or oilseed rape over a six-year period in the region of Galicia, Spain, to identify the rotation system most favorable from a climate change perspective. An attributional life cycle assessment (ALCA) with economic allocation (retrospective assessment of impacts) and a consequential life cycle assessment (CLCA) with system expansion (impacts of a change) were performed to identify discrepancies and differences in the results in this impact category and thus in the decision supported by the farmers, whose main goal is to produce wheat grain for bread purposes with the lowest carbon footprint. The global warming results modelled with ALCA and CLCA can be contradictory. In general, the climate change impact was considerably higher when modelled with CLCA than with ALCA. Farming activities were consistently identified as hotspots when using both CLCA and ALCA, but other hotspots differed in terms of their contributions. Concerning the ranking of cropping systems that produce grain with the lowest greenhouse gases emission levels, contradictory results were identified in some cases between the LCA modelling approaches. Nevertheless, the cultivation of native winter wheat under ecological management is always the preferred choice, regardless of the approach. However, wheat rotation with potato is preferrable in the ALCA, and with maize in the CLCA. The assumptions required to perform a CLCA have a large impact on results. The allocation of burdens between the co-products in the ALCA involves a level of uncertainty since discrepancies arise with the selection of the allocation procedure. Thus, the assumptions made affect the results considerably and have a direct effect on the final conclusions.

Potential environmental impacts of a plastic waste export ban in Germany

Up to 800,000 t/a of plastic waste generated in Germany is exported, of which more than a quarter is packaging. However, a sustainable waste management system aims at treating waste under consideration of environmental benefits generation and the reduction of negative environmental impacts. Thus, this brief research deals with the question to what extent negative environmental impacts could be avoided by an export ban. Further, this brief research serves as a preliminary basis for further discussions and studies in the field of the plastic export ban. Two scenarios were developed based on expert interviews to estimate alternative management for the otherwise exported plastic waste generated in Germany. A consequential life cycle assessment (LCA) was carried out to look into the possible Global Warming Potential changes of such scenarios compared to the current situation scenario. The LCA showed that an export ban in Germany offers the possibility of avoiding up to 80 CO2-equivalent per ton of exported packaging plastic. However, this would be only possible if most of the plastic packaging that is no longer exported is recycled and not burned for energy production in the case of Germany.

Agrivoltaics: The Environmental Impacts of Combining Food Crop Cultivation and Solar Energy Generation

The demand for food and renewable energy is increasing significantly, whereas the availability of land for agricultural use is declining. Agrivoltaic systems (AVS), which combine agricultural production with solar energy generation on the same area, are a promising opportunity with the potential to satisfy this demand while avoiding land-use conflicts. In the current study, a Consequential Life-Cycle Assessment (CLCA) was conducted to holistically assess the environmental consequences arising from a shift from single-use agriculture to AVS in Germany. The results of the study show that the environmental consequences of the installation of overhead AVS on agricultural land are positive and reduce the impacts in 15 of the 16 analysed impact categories especially for climate change, eutrophication and fossil resource use, as well as in the single score assessment, mainly due to the substitution of the marginal energy mix. It was demonstrated that, under certain conditions, AVS can contribute to the extension of renewable energy production resources without reducing food production resources. These include maintaining the agricultural yields underneath the photovoltaic (PV) modules, seeking synergies between solar energy generation and crop production and minimising the loss of good agricultural land.

Consequential-based life cycle assessment of reducing the concentrates supply level in the diet fed to lactating cows in the alpine dairy farming system

This study aimed to assess the consequences of reducing the concentrates supply level (CSL) in the lactating cows’ diet on Alpine dairy system’s GHG emissions. Consequential-based Life Cycle Assessment (cLCA) was adopted to assess the consequences within the ‘dairy_system’ (farm plus milk processing) and outside (‘expanded_system’). The functional unit was 1 kg of protein and fat (ProtFat). Data (1-year average) originated from 40 dairy farms in the Alps, collected through farm questionnaires during farm visits. Emissions were evaluated without (GWP) and with land-based emissions (crop- (GWP_LULUC_cb) or global-based (GWP_LULUC_gb) method). The feed conversion ratio was computed in terms of potentially human-edible gross energy (HeECR, MJ feed/MJ milk). Three scenarios were explored: 100% (t0), 75% (t175), and 50% (t150) of the initial CSL. Impact values for both systems were analysed with a mixed model to test the effect of the scenarios. At ‘dairy_system’, 1 kg ProtFat caused 19.0 (GWP), 22.9 (GWP_LULUC_cb) and 23.4 kg CO2-eq (GWP_LULUC_gb) at t0 and HeECR resulted in 0.71 MJ feed/MJ milk. The CSL reduction from t0 to t175 and t150 significantly increased impact values (2–11%) and decreased HeECR (from −10 to −23%). Considering ‘expanded_system’, CSL reduction significantly increased GWP (4%) and GWP_LULUC_gb (3%) but decreased GWP_LULUC_cb (up to −4%). In conclusion, cLCA-based approach evidenced that CSL reductions implied diversified effects on GHG emissions, at Alpine dairy system and at food supply level, giving new insights into the challenge of reducing GHG emissions while favouring the decoupling of milk production from the use of human-edible resources. Highlights Consequential Life Cycle Assessment of reducing concentrates supply (CSL) to lactating cows on the GHG emission of Alpine dairy products was analysed GHGs per protein plus fat in the product increased with decreasing CSL (75% and 50% of initial CSL) but can decrease considering land-use change GHG Decoupling Alpine dairy production from concentrates could be environmentally challenging but feasible

Environmental consequences of a consumer shift from dairy- to soy-based products

Context Climate change and water scarcity are global challenges facing humanity. Animal agriculture generates considerable greenhouse gas (GHG) emissions and consumes large volumes of water from rivers, streams and lakes. Reducing consumption of animal agricultural products with a relatively high carbon or water footprint, such as dairy, is often promoted as a mechanism to reduce the environmental impacts of food production. Attributionally-based footprints do not, however, assess the consequences of a change in demand for a product. Aims This study aimed to assess the water and climate change consequences of replacing NSW dairy production, and co-products of dairy production, with plant-based alternatives. Methods Process-based consequential life cycle assessment was used. Key results Water savings associated with the change would be limited and GHG emissions reductions would be ~86% of that as estimated by the carbon footprint of production. When NSW dairy production was replaced with soy-based alternatives and two GHG emissions reduction strategies were implemented across the industry, namely enteric methane inhibitors and flaring methane from effluent ponds, GHG emissions increased by 0.63 Mt carbon dioxide equivalent when dairy production was replaced. Conclusions The environmental benefits associated with replacing NSW dairy production with plant-based alternatives should not be determined by attributionally-based approaches. Implications Policies that aim to reduce the environmental impacts of agricultural production need to consider the market effects of a change in demand for products and not rely on estimated impacts of current production.

Proof of concept - using prospective hybrid MFA-LCA to evaluate the environmental implications of Circular Economy using a case study of wood

Consistent evaluations of impacts induced by implementation of Circular Economy (CE) design processes and solutions within the built environment, necessitates decision-support tool development/advancement, as CE does not allow for business-as-usual assessments only. A preliminary test of concept that seeks to quantify the environmental implications of CE on a case study of wood, is presented here.The core methodology is based on coupling of the Shared Socioeconomic Pathways (SSPs) with Material Flow Analysis (MFA) and consequential Life Cycle Assessment (cLCA). Applying this novel approach, a prospective consequential hybrid MFA-LCA analysis was initiated, to evaluate the mitigation challenges of CE design processes, through different formalized and generally accepted (i.e. consensus) scenarios.The case study is based on Danish reference buildings, meeting the current building regulations, designed to replace conventional building materials with wood. This “wood approach” for test of concept case study, is chosen due to the increasing interest in wood construction.The development and calibration of a prospective model for different building material consumptions will further illuminate the connection between the to-be generated emissions and the marginal productions of the materials in question, under specific sets of societal development scenarios.

Life Cycle Assessment and Techno-Economic Analysis for Anaerobic Digestion as Cow Manure Management System

Clean electricity is generated by the anaerobic digestion of biomass waste. The environmental impacts of various biomass waste feedstocks vary, while co-digestion has been reported to improve anaerobic digestion performance. A consequential life-cycle assessment (LCA) and techno-economic analysis (TEA) are carried out for cow manure waste management for a cow farm. Three scenarios are considered in this study: (S1) mono-digestion of cow manure, (S2) co-digestion of cow manure and maize silage, and (S3) co-digestion of cow manure with cow feed waste, sewage sludge, and returned dairy products. The LCA aims to quantify the environmental impact of each MWh of electricity generated, assuming the plant is located in Malaysia, using OpenLCA software. The TEA economic parameters are quantified and compared between the three scenarios. Net present value (NPV), Internal Return Rate (IRR), and Return of Investment (ROI) are examined. Among the three scenarios, S2 with maize cultivation has a higher environmental impact due to its higher energy requirements. With the integration of closed digestate storage and renewable energy-powered electricity, S3 has the best environmental performance in global warming, eutrophication and acidification. S3 is found to be most economically viable, with MYR 1.28 million NPV, 14% IRR, and 15% ROI, and a Payback Period of 6.56 years with an OPEX of MYR 3491.82/MWh.

A systematic review of consequential LCA on buildings: the perspectives and challenges of applications and inventory modelling

A systematic review of consequential LCA on buildings: the perspectives and challenges of applications and inventory modelling

Greenhouse gas emissions from hybrid energy storage systems in future 100% renewable power systems – A Swedish case based on consequential life cycle assessment

To promote the development of renewables, this article evaluates the life cycle greenhouse gas (GHG) emissions from hybrid energy storage systems (HESSs) in 100% renewable power systems. The consequential life cycle assessment (CLCA) approach is applied to evaluate and forecast the environmental implications of HESSs. Based on the power system of Sweden, different HESS combinations, which include energy storage (ES) technologies: pumped hydro ES, hydrogen ES, lithium-ion (Li-ion) batteries, lead-acid (PbA) batteries, vanadium redox (VR) batteries, supercapacitors (SCs), and flywheels, are discussed. The results show that for Sweden and similar large-scale utility applications, the cradle-to-gate GHG emissions from the HESS contribute to a major share of the life cycle GHG emissions due to the under-utilization of the cycle life. Among the HESSs compared in this study, the Pumped hydro+Li-ion+Flywheel combination exhibits the least life cycle GHG emissions. Moreover, the phasing out of nuclear power brings a severe challenge to the carbon reduction target. However, the introduced HESS manages to reduce GHG emissions from a 100% renewable power system.

Consequential life-cycle assessment of treatment options for repulping reject from liquid packaging board waste treatment

Liquid packaging board is one of the highly demanded packaging mediums for liquid food and beverages, generating substantial waste each year. Even though the fibre part of the liquid packaging board is recycled through a repulping process, the plastic and aluminium are usually used for energy recovery and as alternative raw materials in cement factories. This practice reduces the life span and economic value of plastic and aluminium, which does not fit within a circular economy. The plastic and aluminium from liquid packaging board waste can be recycled mechanically and chemically. This study used the consequential life-cycle assessment method to compare the environmental impact of the recovery options of rejected materials from liquid packaging board waste treatment. Four scenarios were established: (1) energy recovery by waste incineration, (2) composite pallet production by mechanical recycling, (3) plastic pallet production by mechanical recycling, and (4) plastic pallet production by chemical recycling. The study showed that when the consumed energy was supplied from renewable sources, plastic pallet production by mechanical recycling process had the lowest environmental impact, and energy recovery by waste incineration had the highest impact. A sensitivity analysis revealed that composite pallet production by mechanical recycling process showed the best impact if the energy was sourced from the average production mix, and plastic pallet production by chemical recycling had the lowest impact when mechanically recycled plastic substituted for 0%, 30%, and 50% of virgin plastic. These results should be of interest to liquid packaging board manufacturers and other related stakeholders.

Environmental benefits of circular food systems: The case of upcycled protein recovered using genome edited potato

Although essential in the human diet, large quantities of available protein are currently lost or under-utilized within the food system, including protein rich side streams from conventional potato starch production. By using the genome editing technique CRISPR-Cas9, conventional starch potato cultivars can be upgraded to facilitate high-value recovery of potato protein fit for human consumption. In turn, this could support the nessecary transition towards more circular food systems. The aim of this study was to assess what environmental benefits could be gained by shifting from conventional protein recovery practice to a novel approach using genome edited potato. Our results, using consequential life cycle assessment, showed that the novel protein recovery scenario provided substantial environmental savings for every ton potato starch produced, with a reduction in global warming impact, terrestrial acidification, land use and ecosystem damage of −720 kgCO2eq, −13 kgSO2eq, −760 m2a crop eq, and −1.1 × 10−5 species.yr respectively. The potential environmental benefits of using genome edited potato were maintained even when simulating reduced tuber yield, increased production inputs, and substitution of various protein sources. Although currently limited by EU legislation and technical maturity, high-value protein recovery from food side streams holds a promising potential to support sustainable production and circularity within the food system.

Dynamic LCA of the increased use of wood in buildings and its consequences: Integration of CO2 sequestration and material substitutions

Wood products can have a lower impact on climate change (CC) than other building materials, and their carbon content can transform buildings into temporary carbon sinks. However, the large-scale use of wood products in buildings requires a better understanding of their consequences to support CC policies. The consequential life cycle inventory of such products contains elementary flows with values sometimes greater sometimes less than zero. Therefore, their static assessment did not show the influence of carbon uptake and release, either during or after the temporal boundary of the system. The originality lies in the combination of the dynamic modeling of tree harvesting and growth, temporary carbon storage, end-of-life (EOL) strategies, material substitution, and characterization factors in a consequential life cycle assessment (LCA). This combination highlights the extent to which material substitution, EOL strategies, and carbon sequestration can be decisive. In addition, it addresses the static and dynamic measurements of radiative forcing (W.m−2) and the carbon dioxide (CO2) equivalent (CO2eq.). In this case study, material substitution contributed the most to result, followed by post-harvest CO2 sequestration. In terms of metrics, the conventional static LCA overestimates the long-term cumulative impact on CC (tonne CO2eq.) without providing information on the short-term impact of the case study. In addition, the assessment of such a dynamic consequential life cycle inventory (LCI) with a dynamic metric provides more specific information, regardless of the temporal boundary. However, the absolute dynamic metrics (W.m−2) should support the relative dynamic metric (tonne CO2eq.1st year) to avoid misleading conclusions.

Stochastic Ex-Ante LCA under Multidimensional Uncertainty: Anticipating the Production of Undiscovered Microalgal Compounds in Europe.

Due to their biodiversity, microalgae represent a promising source of high-value compounds that bioprospecting is aiming to reveal. Performing an ex-ante Life Cycle Assessment (LCA) to anticipate and potentially minimize the environmental burden associated with the European production of a bioprospected microalgal compound is subject to substantial and multi-factorial uncertainty as the compound remains undiscovered. Given that any microalgal strain could potentially host the compound of interest, the ex-ante LCA should consider this bioprospecting uncertainty together with the uncertainty on the technology and the production mix. Using a parameterized cultivation simulation and consequential LCA model and an extensive stochastic pseudo Monte Carlo approach, we define and propagate techno-operational, bioprospecting, and production mix uncertainties for a microalgal compound being currently bioprospected in Europe. We perform global sensitivity analysis using different sampling strategies to identify the main contributors to the total output variance. Overall, the uncertainty propagation allowed us to define and analyze the probabilistic scope for the potential environmental impacts in the emerging production of high-value microalgal compounds in Europe based on current knowledge. These findings can support policy-making as well as actors in the microalgal sector toward technological paths with lower environmental impact.

Fish oil substitution with vegetable oils in diets for greater amberjack (Seriola dumerili): A consequential life cycle assessment approach

This study assessed the environmental impacts of substituting fish oil with vegetable oils in the diets of greater amberjack (Seriola dumerili), based on both attributional and consequential life cycle assessments. The dietary lipid source was either fish oil (FO diet) or a blend of vegetable oils (linseed oil, sunflower oil, and palm oil, 4:3:3; VO diet). From an attributional perspective, the production of 1 kg of the FO diet released 1.10 kg CO2-eq and 1.60 kg CO2-eq as for global warming potential with and without land-use change, and 8.6 g PO4-eq as for the eutrophication potential; the depleted stock fraction index was equivalent to 2.8E−07. Compared with the FO diet, the production of 1 kg of the VO diet increased global warming potential with and without land-use change (by 5% and 4%, respectively) and PO4-eq by 58%, and reduced depleted stock fraction index by 24%. Consequential modelling revealed that in a scenario using fish oil and fishmeal derived from fish by-products, the marginal production of 1 kg of the VO diet compared with that of the FO diet produced a lower global warming potential with (−19%) and without land-use change (−12%), a greater eutrophication potential (+33%), and reduced depleted stock fraction index (−23%). In a scenario using fish oil and fishmeal diverted from a pre-existing fish production system, compared with that of the FO diet, the marginal production of 1 kg of the VO diet yielded similar values of global warming potentials and depleted stock fraction index, and a considerably higher eutrophication potential (+44%) value. For both FO and VO diets, fish-derived products (oil and meal) notably contributed to global warming potentials, as determined using both the attributional and consequential approaches. In contrast, the two diets differed with respect to the major contribution to eutrophication potential, which originated from non-fish-derived constituents for the FO diet and from vegetable oils (particularly sunflower oil) for the VO diet. Sensitivity analysis indicated that the replacement of sunflower oil with an equal quantity of another oil, e.g. palm oil, could reduce the eutrophication potential of the VO diet. In conclusion, the substitution of fish oil in aquafeeds with a mixture of vegetable oils could contribute to reductions in the exploitation of wild fish stocks and greenhouse gas emissions, although potential trade-offs, such as increased eutrophication, should be taken into consideration to enhance the environmental sustainability of aquafeed production based on an integrated approach.